Fig. 3 represents: — the proventricular sac thrust forward, f g h; the
gizzard, h; the duodenum, i j k, pulled to the right side; the convolutions
of the intestine, / m, under the kidneys; the coeca, n; the rectum, o; and
the cloaca, p.
The proventricular glands are very numerous, but not so closely placed as is usual, although scattered over a much larger extent, from e to g, in Fig. 2. Between the termination of the glands and the stomach there is a portion destitute of glandules. The stomach or gizzard has its muscular coat thick, its tendons moderate, its inner surface covered with a rather thick but not very hard epithelium, which is more prolonged on two opposite sides, although in the fundus it is complete.
This curious digestive apparatus agrees very nearly with that described and figured by Sir Everard Home as that of Alca Mle. The stomach, it is seen, is excessively large in proportion to the size of the bird; but why it should be so, and moreover be curved in this manner, is not very obvious.
Conjectures are easily made, and might run in this form. This little bird, which wanders over the face of the ocean, subsisting upon garbage, oily and fatty substances, small fishes, and even sea-weeds, requires a large stomach for the reception of its heterogeneous fare, which not being always very nutritious or easily digestible, must be very plentifully intermixed with the gastric juices, and detained a considerable time; which conditions are accordingly provided for by the very great number and extensive dispersion of the proventricular glandules, and the curve of the organ. Should any hard substances, as Crustacea, be introduced, they are pounded by the gizzard; but as the bird is little addicted to feeding on such substances, that organ is reduced to a very small size.
The aperture of the glottis is twelfths long. The trachea is 1 inch 7 twelfths in length, wide, flattened, its diameter from 2 twelfths to 1^ twelfths; its rings unossified, S2 in number. The bronchi are short, wide, of about 12 half rin°;s.
